Monolithic microwave integrated circuit (MMIC) amplifiers are typically used to amplify high frequency RF and/or microwave signals. Increasing the RF gain (or amplification) in amplifiers, such as MMIC driver/power amplifiers, typically requires increasing the number of amplification stages, which is accomplished by increasing the number of transistors. Unfortunately, there is generally a sharp correlation between increasing the amplification and the design cost. This is due largely in part because as the amplification increases, the space needed on the die for amplification also increases and therefore the size of the die must also increase. Thus, it would be desirable to increase the signal amplification in a driver amplifier without causing an increase in the size of the die.
Accordingly, there exists a need for a driver amplifier with a reduced die size. In addition, there is a need for a low cost driver amplifier. Further, there is a need for improved performance driver amplifiers having higher gain and increased efficiency.
Various attempts have been proposed to reduce the die size of power amplifiers, such as that disclosed by Buer et al., U.S. Pat. No. 6,388,528. Buer proposes a “folded field effect transistor (FET)” configuration to pack the transistors into a compact area. Buer also discloses a power splitting/power combining configuration reducing the die area.